1. Field of the Invention
The present invention relates to an inkjet recording apparatus and an inkjet recording method that record an image on a recording medium by ejecting ink and generating correction data on the basis of colorimetric results of the recorded image.
2. Description of the Related Art
With an inkjet recording apparatus including recording heads having a plurality of inkjet ejecting ports (nozzles), the recorded image will have uneven color density (nonuniform color density) due to a variation in the ejecting characteristic of the nozzles. With serial recording in which image recording is performed by scanning a recording head with respect to a predetermined area on a recording medium multiple times, uneven color density can be easily prevented by multi-path recording. On the other hand, it is difficult to prevent unevenness in color density by line-head single path recording in which an image is recorded in one scanning operation using a wide line head having a nozzle array corresponding to the width of a sheet.
To improve the quality of an image recorded with a line head, it is important to correctly measure and analyze the color density evenness and perform correction (output correction) during recording on the basis of the measurement and analysis results. Specifically, this is a technique that provides a high quality image by recording test patterns using the nozzles, measuring the color density through image analysis, and determining the recording color density. As such a technique, Japanese Patent Laid-Open No. 10-13674 discusses a head shading technique in which information about the volume of ink ejected from each ink ejecting nozzle is acquired, and the number of recording dots is modified in accordance with the information about ink volume. Furthermore, Japanese Patent Laid-Open No. 2000-334935 discusses a technique in which evenness is maintained by detecting abnormal nozzles and terminating use of such abnormal nozzles.
To correct unevenness in color density of a recorded image caused by a variation in the ejecting characteristic of nozzles, as described above, correction test patterns are recorded on the recording medium to be used, and color density data for generating correction data is acquired. At this time, there is a limit to the size of a usable recording medium. Therefore, in some cases, color density data for correcting all nozzles on a recording head may not be acquired at once. This will be described below.
FIG. 1 is a schematic view of a recording head and recording media. In the drawing, the recording medium is conveyed in the x direction, and the nozzle array on the recording head extends in the y direction. Details of the configuration and control of an inkjet recording head 111 will be described below. The widths of recording media 112 and 113 in the y direction depend on, for example, the product. The recording head 111 is capable of recording an image on an area wider than the width of the recording medium. The recording head 111 has such recording as a result of taking into consideration so-called “frameless recording” in which an image is record on the entire area of the recording medium, an error in the conveying conditions of the recording medium, and the manufacturing tolerance of the width of the recording medium. Therefore, the recording head 111 is designed to have a nozzle width greater than the maximum width (maximum guaranteed width) of a feedable recording medium.
Due to the above-described reason, image data corresponding to the nozzles of the recording head 111 should be corrected, and color density data is acquired by recording a correction test pattern and performing colorimetry on this. When the nozzle width of the recording head is greater than the maximum guaranteed width, color density data for only the nozzles corresponding to the maximum guaranteed width can be acquired in one recording operation. When cases in which the positions of the corrected nozzles and the recording medium are not aligned due to error in the conveying condition of the recording medium and frameless recording is performed are taken into consideration, there is a problem in that correcting only the nozzle corresponding to the maximum guaranteed width is insufficient.